We found this circuit in a magazine 73 from the 90's. It is a circuit indicated for radio-amateur transmitters with the frequencies determined by the sets of coils.
This circuit is from an old publication from 1977 and can be implemented with more modern...
This basic buffer circuit can be implemented with other operational amplifiers. The circuit is...
This circuit can be applied to other 3-terminal regulators and equivalent transistors can be used....